How to create a material that is part solid, part transparent wireframe?
In Blender Internal render engine, you can use Freestyle. To enable freestyle - Go to the render panel and click freestyle - 

Then go to edit mode, select the edges that you want to render and press "Crtl+E"
and click "mark freestyle edge".


Then go to "Render Layers", click on the Line set that should be automaticly created and click only on "edge mark"


Then on the tab "freestyle line style", you have options for the lines.

Then you can click on render.